A converter station is known from the lecture “A study of +/−500 kV, 2400 MW compact converter station”, whose authors were D. E. Fletcher, D. L. Gordon, R. E. Harrison, M. A. Lebow and R. Mauro at the “IEE International Conference on AC and DC Power Transmission” on Sep. 17-20, 1991, and was published in London, United Kingdom, under the ISBN Number 0-85296-517-6, in 1991, on pages 165-170 of Volume 345 of “AC and DC Power Transmission”. The design described there for a compact converter station develops a concept for the accommodation of a converter station for high-voltage DC transmission in a closed multistory building. The converter station has converter valves which extend over a number of floors and are mounted in a suspended fashion in valve halls. Filter units are provided on the top floor of the converter building, and above the valve halls, in order to suppress the harmonics, which occur during conversion, in the three-phase network. Three transformer cells with a transformer unit as well as a reactor chamber with an oil-cooled smoothing reactor are arranged on the first floor, alongside the valve halls. An underground Cable room is provided between the valve halls and the transformer cells. The connections of a three-phase AC cable penetrate project into the cable room, with the electrical power being carried within the building by gas-insulated busbars or cables, some of which extend through the cable ducts.
The DC voltage which is coming to to the converter station is first of all connected to the oil-cooled smoothing reactor; and is supplied to the converter valves via a deacated bushing. Once the direct current has been converted to alternating current, the AC voltage which is produced has its voltage changed by the transformer unit to an AC voltage that is intended for further distribution, while AC filter units are used to remove the harmonics, some of which are produced, during the conversion process. After voltage conversion and filtering, the alternating current is fed to the desired AC network via an AC cable which penetrates into the cable area. For power interruption and for no-load disconnection flowing, gas-insulated switchgear assemblies are provided on both the DC side and the AC side in the building, and are arranged on the fourth and fifth floors, above the transformer chamber.
The objective of the design described above is to reduce the physical volume of conventional converter stations. As a rule, conventional converter stations are arranged in low-population regions, so that it is possible to make use of the availability of a sufficiently large amount of space. Conventional converter stations are thus designed as open-air installations, and cover large areas. The known design discloses ideas to make it possible to offer converter stations at a low cost in densely populated regions where the land prices are high, while at the same time maintaining the aim of complying with standard safety requirements.
The described design of a converter station is subject to the disadvantage that implementation of the design would be costly and would lead to a physically interleaved building in order to accommodate the converter station.
The lecture by P. Lips, “Compact HVDC Converter Station Design Considerations” which appeared in “IEEE Transactions on Power Apparatus and Systems, Vol. PAS-9.5, No. 3 (1976)”, discloses a converter station to be arranged in a multistory building. Smoothing reactors, transformer units and converter valves are arranged on the first floor in the building disclosed there. On the floor above this, DC cable terminations are each electrically connected to an isolating switch in order to interrupt the DC connection in an inert gas atmosphere, with the isolating switch being connected to the smoothing reactor via a gas-insulated conductor connection. The gas insulated conductor is routed, which across a number of floors, between the DC cable termination, the isolating switch and the smoothing reacotor, is however, associated with additional cost. Furthermore, with a design such as this, the high-voltage DC cables which are routed to the station should be routed in a complex manner via the basement, passing by the oil-cooled DC smoothing reactors which are arranged on the first floor, to the DC cable pot-head on the second floor. An appropriately running cable riser duct is therefore provided in the abovementioned converter station and is equipped in a costly manner with fire barriers in order to prevent fire from propagating between the different floors.